Seal assembly

ABSTRACT

A seal assembly is provided that includes an elastomeric portion; a primary extrusion barrier which reinforces the elastomeric portion; and a secondary extrusion barrier disposed between the elastomeric portion and the primary extrusion barrier to prevent entry of the elastomeric portion into open areas in the primary extrusion barrier.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application Ser. No. 60/715,428, filed on Sep. 9, 2005,which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a seal assembly, such as aseal assembly for use with a well bore packing tool (commonly referredto as “packer”), and particularly to a seal assembly having anelastomeric material portion, and primary and secondary extrusionbarrier portions, which reinforce the elastomeric material portion andincrease the life and durability of the seal assembly.

BACKGROUND

Seal assemblies, such as those used on well bore packers are typicallycylindrically shaped structures having an inner diameter disposed insurrounding relation to a first device, such as a packer, and an outerdiameter that may be forced into sealing engagement with a seconddevice, such as an inner diameter of a casing segment.

For such applications, seal assemblies typically include an elastomericmaterial portion, which may be deformed to extend radially outwardly tosealingly engage the inner diameter of the casing segment. However,during such a sealing engagement, the elastomeric material has atendency to extrude, or extend, longitudinally along the inner diameterof the casing segment. Such a movement of the elastomeric materialdecreases the sealing efficiency of the elastomeric material.

As such, some seal assemblies include an extrusion barrier disposedadjacent to the elastomeric material at the open ended portions of theseal assembly. Such extrusion barriers reinforce the elastomericmaterial, while preventing (or at least reducing) the extrusion of theelastomeric material longitudinally along the inner diameter of thecasing segment, thus improving the sealing efficiency of the elastomericmaterial.

A problem with such a configuration is that, during deformation,portions of the elastomeric material often extend into expanded areas inthe extrusion barrier. For example, in instances where the extrusionbarrier is a coil spring, during deformation the elastomeric materialtends to extend into the expanded areas between the coils. As such, asthe elastomeric material returns to its pre-deformed shape, theextrusion barrier often pulls at or pinches the elastomeric material asthe elastomeric material exits the expanded areas in the extrusionbarrier. This causes the elastomeric material to wear at an undesirablyhigh rate. This type of wear is commonly associated with, but notlimited to, applications which require multiple sets of a packer (i.e.when the seals of a packer are alternately sealed and unsealed multipletimes) with the application of multiple high pressure differentialsapplied across the seal. These cyclic, loading and unloading conditionson the seal promote deterioration of the seal body.

Accordingly, a need exists for a seal assembly having an improvedextrusion barrier portion, which increases the life and durability ofthe seal assembly.

SUMMARY

In one embodiment, the present invention is a seal assembly thatincludes an elastomeric portion; a primary extrusion barrier whichreinforces the elastomeric portion; and a secondary extrusion barrierdisposed between the elastomeric portion and the primary extrusionbarrier to prevent entry of the elastomeric portion into open areas inthe primary extrusion barrier.

In another embodiment, the present invention is a seal assembly thatincludes an elastomeric portion; a primary extrusion barrier, which ismore rigid than the elastomeric portion to reinforce the elastomericportion; and a secondary extrusion barrier disposed between theelastomeric portion and the primary extrusion barrier, which is moredense than the elastomeric portion to prevent entry of the elastomericportion into open areas in the primary extrusion barrier.

In yet another embodiment, the present invention is a well bore packerthat includes a packer mandrel; and either of the seal assembliesdescribed above disposed in surrounding relation to the packer mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is side view of an upper portion of a well bore packer having aseal assembly according to one embodiment of the present inventiondisposed thereon;

FIG. 2 is a longitudinal cross-sectional view of a well bore packerhaving a seal assembly according to another embodiment of the presentinvention disposed thereon; and

FIG. 3 is a longitudinal cross-sectional view of a well bore packerhaving a seal assembly according to yet another embodiment of thepresent invention disposed thereon.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As shown in FIGS. 1-3, embodiments of the present invention are directedto a seal assembly. The seal assembly includes an elastomeric materialportion, and a primary extrusion barrier for reinforcing the elastomericmaterial portion. Disposed between the elastomeric material portion andthe primary extrusion barrier is a secondary extrusion barrier. Thesecondary extrusion barrier prevents the elastomeric material portionfrom extruding, or extending, into the primary extrusion barrier duringdeformation of the elastomeric material portion. If the elastomericmaterial portion is allowed to extrude into the primary extrusionbarrier, the elastomeric material portion wears at an undesirably highrate. As such, the secondary extrusion barrier increases the life anddurability of the seal assembly.

FIG. 1 shows a seal assembly 10 according to one embodiment of thepresent invention. Although a seal assembly according to the presentinvention may be used in conjunction with any appropriate device, in thedepicted embodiment, the seal assembly is disposed on a well bore packer12 (note, for clarity purposes, only the upper portion of the packer isshown.)

The packer 12 may be any appropriate packer, such as that described inU.S. Pat. App. No. 60/652,805, entitled “Packer for Spirit Tool”, andrelated non-provisional filed on Aug. 26, 2005(Atty. Dk. No. 25.0316),the entire contents of which is hereby incorporated by reference. Whenused in combination with a well bore packer, the seal assembly 10 may beused for multi-layer, perforating, and stimulation applications, ordownhole annular barrier applications, among other appropriateapplications.

FIG. 2 shows a seal assembly 10′ according to another embodiment of thepresent invention. As shown, the seal assembly 10′ is a generallycylindrically shaped hollow tube having an inner diameter disposed insurrounding relation to a packer mandrel 14 of a well bore packer 12′.

In the depicted embodiment, the seal assembly 10′ includes anelastomeric material portion 16, a primary extrusion barrier 18, and asecondary extrusion barrier 20. The elastomeric material portion 16 maybe composed of any material, such as any one of a variety of well knownmaterials appropriate for creating fluid and/or pressure seals.

Disposed at each longitudinal end of the elastomeric material portion 16is a primary extrusion barrier 18. The primary extrusion barrier 18reinforces the elastomeric material portion 16 to provide addedstructural and stability to the seal assembly 10′. As such, in oneembodiment the primary extrusion barrier 18 is composed of a materialwhich is stronger or more rigid than the elastomeric material portion16. For example, exemplary primary extrusion barrier 18 materialsinclude coil springs, c-rings, wave springs and/or any combinationthereof, among other appropriate materials. Disposed between theelastomeric material portion 16 and the primary extrusion barrier 18 isthe secondary extrusion barrier 20, the utility of which is described indetail below.

In one embodiment, the seal assembly 10′ is deformed by a mechanical,hydraulic, or electrically generated force applied at the ends of theseal assembly 10′. As the seal assembly 10′ is compressed in thismanner, the elastomeric material portion 16 is constricted on its endsand forced to expand in a radial direction until it comes into contactwith and sealingly engages a target seal area, such as the innerdiameter of a casing segment (not shown.)

During this compression, the primary extrusion barrier 18 is also forcedin the radial direction into contact with the casing segment. Theprimary extrusion barrier 18, thus positioned, prevents the elastomericmaterial portion 16 from extruding or extending therepast in alongitudinal direction along the inner diameter of the casing segment.The primary extrusion barrier 18 thus improves the sealing efficiency ofthe elastomeric material portion 16 with the inner diameter of thecasing segment.

However, as described above, the radial movement of the primaryextrusion barrier 18 may create openings or expanded areas into whichthe elastomeric material portion 16 may extend when compressed, which ifallowed to occur would cause the elastomeric material portion 16 to wearat an undesirably high rate. To alleviate this problem, the secondaryextrusion barrier 20 is disposed between the elastomeric materialportion 16 and the primary extrusion barrier 18. As with the primaryextrusion barrier 18, during the compression of the seal assembly 10′,the secondary extrusion barrier 20 is also forced in the radialdirection into contact with the casing segment.

Thus positioned, the secondary extrusion barrier 20 acts as a flowbarrier, which resists the flow of the heated or pressurized elastomericmaterial portion 16 into the primary extrusion barrier 18. As a result,the secondary extrusion barrier 20 increases the life and durability ofthe seal assembly 10′ by eliminating the extrusion of the elastomericmaterial portion 16 into any expanded or open areas in the primaryextrusion barrier 18.

In order to prevent the flow of the elastomeric material portion 16 intothe expanded or open areas in the primary extrusion barrier 18, in oneembodiment the secondary extrusion barrier 20 is composed of a materialwhich is more dense than the elastomeric material portion 16. Forexample, exemplary secondary extrusion barrier 20 materials includewire, Aramid fiber, carbon fiber, foam, or plastic, and/or anycombination thereof, arranged in a mesh, wrapped, woven, or solidconfiguration.

Alternatively, the secondary extrusion barrier 20 may be composed of anyother material, arranged in any other configuration, which is suitablefor preventing the extrusion of the elastomeric material portion 16 intothe primary extrusion barrier 18 during compression of the seal assembly10′. Exemplary materials for the elastomeric material portion 16 includea Hydrogenated Nitrile (HNBR) elastomeric compound, a Nitrile (NBR)compound, or an Aflas compound, among other materials capable of formingan appropriate seal.

In one embodiment, the elastomeric material portion 16 is composed of aHydrogenated Nitrile (HNBR) elastomeric compound, the primary extrusionbarrier 18 is composed of a looped coil spring, and the secondaryextrusion barrier 20 is composed of a woven wire mesh fabric.

In one embodiment, the secondary extrusion barrier 20 is formed aroundthe primary extrusion barrier 18 and the combination of the primary andsecondary extrusion barriers 18 and 20 is attached to the elastomericmaterial portion 16 in a compression molding process. In an alternativeembodiment, the extrusion barriers 18 and 20 may be placed in serieswith the elastomeric material portion 16 rather than being moldedthereto.

The geometry of the secondary extrusion barrier 20 is not limited tothat shown in FIG. 2. Also, in one embodiment the secondary extrusionbarrier 20 completely encloses the primary extrusion barrier 18.However, it is only necessary that the secondary extrusion barrier 20forms a barrier between the elastomeric material portion 16 and theprimary extrusion barrier 18. Thus, although possible, is it notnecessary for the secondary extrusion barrier 20 to completely enclosethe primary extrusion barrier 18.

The seal assembly may be a one piece seal (as is shown in FIG. 2) or amultiple section seal (is shown in FIGS. 1 and 3). FIG. 3 shows amultiple section seal. However, the descriptions and variationsdescribed above with respect to FIG. 2 apply to FIG. 3. As such, inorder to avoid duplicity, only the differences between FIGS. 2 and 3 arediscussed herein. For instance, the seal assembly 10″ of FIG. 3 includesa first elastomeric material portion 16″, and a second elastomericmaterial portion 22, disposed between the first elastomeric materialportion 16″ and the secondary extrusion barrier 20. In one embodimentthe second elastomeric material portion 22 is composed of a hardermaterial than the first elastomeric material portion 16″.

Exemplary materials for the elastomeric material portions 16″ and 22include a Hydrogenated Nitrile (HNBR) elastomeric compound, a Nitrile(NBR) compound, or an Aflas compound, among other materials capable offorming an appropriate seal.

In one embodiment the first elastomeric material portion 16″ is composedof a Hydrogenated Nitrile (HNBR) elastomeric compound, and the secondelastomeric material portion 22 is also composed of a HydrogenatedNitrile (HNBR) elastomeric compound, but one having a greater hardnessthan that of the first elastomeric material portion 16″.

Although FIGS. 2 and 3 each show extrusion barriers at each longitudinalend of the seal assembly, one skilled in the art will appreciate that itis only necessary for one longitudinal end of the seal assembly toinclude the extrusion barriers. Also, although the above descriptionfocuses on the seal assembly 10′ being used in combination with a wellbore packer to form a seal with the inner diameter of a casing segment,one skilled in the art will appreciate that a seal assembly according tothe present invention may be used on any appropriate device to form anyappropriate seal.

It is to be noted that each of the seal assemblies described abovemaintains structural integrity over multiple sets and differentialpressure applications, without excessive deterioration of theelastomeric portion(s) of the seal assemblies.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Persons skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structures and methods ofoperation can be practiced without meaningfully departing from theprinciple, spirit and scope of this invention. Accordingly, theforegoing description should not be read as pertaining only to theprecise structures described and shown in the accompanying drawings, butrather should be read as consistent with and as support for thefollowing claims, which are to have their fullest and fairest scope.

1. A seal assembly comprising: an elastomeric portion; a primaryextrusion barrier which reinforces the elastomeric portion; and asecondary extrusion barrier disposed between the elastomeric portion andthe primary extrusion barrier to prevent entry of the elastomericportion into open areas in the primary extrusion barrier.
 2. The sealassembly of claim 1, wherein the primary extrusion barrier is more rigidthan the elastomeric portion.
 3. The seal assembly of claim 2, whereinthe primary extrusion barrier comprises a material chosen from the groupconsisting of coil springs, c-rings, and wave springs.
 4. The sealassembly of claim 1, wherein the secondary extrusion barrier is moredense than the elastomeric portion.
 5. The seal assembly of claim 4,wherein the secondary extrusion barrier comprises a material chosen fromthe group consisting of wire, Aramid fiber, carbon fiber, foam, andplastic.
 6. The seal assembly of claim 5, wherein the secondaryextrusion barrier material comprises a configuration chosen from thegroup consisting of mesh, wrapped, woven, and solid.
 7. The sealassembly of claim 1, wherein the primary extrusion barrier comprises acoil spring, and the secondary extrusion barrier comprises a woven wiremesh fabric.
 8. The seal assembly of claim 7, wherein the elastomericportion comprises a material chosen from the group consisting of aHydrogenated Nitrile compound, a Nitrile compound, and an Aflascompound.
 9. The seal assembly of claim 1, wherein the elastomericportion is a first elastomeric portion, and wherein the seal assemblyfurther comprises a second elastomeric portion, which is adjacent to thefirst elastomeric portion.
 10. A seal assembly comprising: anelastomeric portion; a primary extrusion barrier, which is more rigidthan the elastomeric portion to reinforce the elastomeric portion; and asecondary extrusion barrier disposed between the elastomeric portion andthe primary extrusion barrier, which is more dense than the elastomericportion to prevent entry of the elastomeric portion into open areas inthe primary extrusion barrier.
 11. The seal assembly of claim 10,wherein the secondary extrusion barrier comprises a material chosen fromthe group consisting of wire, Aramid fiber, carbon fiber, foam, andplastic.
 12. The seal assembly of claim 11, wherein the secondaryextrusion barrier material comprises a configuration chosen from thegroup consisting of mesh, wrapped, woven, and solid.
 13. The sealassembly of claim 11, wherein the primary extrusion barrier comprises amaterial chosen from the group consisting of coil springs, c-rings, andwave springs.
 14. The seal assembly of claim 10, wherein the primaryextrusion barrier comprises a coil spring, and the secondary extrusionbarrier comprises a woven wire mesh fabric.
 15. The seal assembly ofclaim 14, wherein the elastomeric portion comprises a material chosenfrom the group consisting of a Hydrogenated Nitrile compound, a Nitrilecompound, and an Aflas compound.
 16. The seal assembly of claim 10,wherein the elastomeric portion is a first elastomeric portion, andwherein the seal assembly further comprises a second elastomericportion, which is adjacent to the first elastomeric portion.
 17. A wellbore packer comprising: a packer mandrel; and a seal assembly disposedin surrounding relation to the packer mandrel, wherein the seal assemblycomprises: an elastomeric portion, a primary extrusion barrier, which ismore rigid than the elastomeric portion to reinforce the elastomericportion, and a secondary extrusion barrier disposed between theelastomeric portion and the primary extrusion barrier, which is moredense than the elastomeric portion to prevent entry of the elastomericportion into open areas in the primary extrusion barrier.
 18. The sealassembly of claim 17, wherein the secondary extrusion barrier comprisesa material chosen from the group consisting of wire, Aramid fiber,carbon fiber, foam, and plastic.
 19. The seal assembly of claim 18,wherein the secondary extrusion barrier material comprises aconfiguration chosen from the group consisting of mesh, wrapped, woven,and solid.
 20. The seal assembly of claim 18, wherein the primaryextrusion barrier comprises a material chosen from the group consistingof coil springs, c-rings, and wave springs.
 21. The seal assembly ofclaim 17, wherein the primary extrusion barrier comprises a coil spring,and the secondary extrusion barrier comprises a woven wire mesh fabric.22. The seal assembly of claim 21, wherein the elastomeric portioncomprises a material chosen from the group consisting of a HydrogenatedNitrile compound, a Nitrile compound, and an Aflas compound.
 23. Theseal assembly of claim 17, wherein the elastomeric portion is a firstelastomeric portion, and wherein the seal assembly further comprises asecond elastomeric portion, which is adjacent to the first elastomericportion.